Changes in weather pattern and the air quality have affected the lifestyle of people all over the world. Major causes have been identified including global warming due to greenhouse gases such as CO2, CO, NOx, and other pollutants released from many sources. Further analysis shows that coal-based utilities are responsible as one of the main impact sources. Hence, many research efforts are now focusing on process avenues such as enhancing power plant efficiency to reduce CO2 production per kWh of electricity and cost-effective sequestration of CO2. The CO2 sequestration can be a beneficial approach for the long-term use of coal.
Current pollution control research priorities to sustain coal use in utility applications include volatile metal control such as mercury in addition to SO2 and NOx reduction. The research findings so far on mercury control technologies show that one control technology may not be applicable for all coal types and mercury capture in subbituminous and lignite-fired units may be very difficult. One of the mercury emission control technologies may include thermal treatment of coal. Generally, the temperature regimes, the method of thermal treatment, and the like may vary between the processes. An example of one process is shown in U.S. Pat. No. 5,403,365 to Merriam et. al.
Currently, no full scale subbituminous or lignite coal drying process are commercially operating. The developmental issues for a commercial application may include energy efficiency involved in the pre-processing steps. It may be desirable to avail a heat source, medium, or the like to effectively remove moisture and perhaps at the same time inert enough to raise the temperature of a heating medium to raise a coal temperature to a sufficient level so as to evolve a significant fraction of volatile metals.
Embodiments of the present inventions may define the capabilities of a novel integrated and efficient technology scheme to reduce emission of CO2, volatile metals, and perhaps even other pollutants such as per kWh of the electricity generated and also reduce the cost of electricity generated by perhaps at least about 10% from the current levels.